Polyesters, especially poly(alkylene terephthalate)s, have excellent physical and chemical properties and have been widely used for resins, films and fibers. In particular, polyester fibers have a high melting point, and can attain high orientation and crystallinity. Accordingly, polyesters have properties that are highly desirable in fibers, such as chemical, heat and light stability, and high strength.
The term poly(alkylene terephthalate) is well known to those skilled in the art, and encompasses, for example, poly(trimethylene terephthalate), poly(tetramethylene terephthalate), and poly(ethylene terephthalate). Poly(trimethylene terephthalate), also called poly(1,3-propyleneterephthalate) is prepared from terephthalic acid, or an ester thereof, and 1,3-propylene glycol (1,3-propanediol). The abbreviation “3GT” is also used to refer to poly(trimethylene terephthalate). Poly(tetramethylene terephthalate), also called poly(butylene terephthalate) or 4GT, is prepared from terephthalic acid or an ester thereof and 1,4-butanediol.
Some fluorescent polymers and oligomers are known. For Example, Weaver et al., in U.S. Pat. No. 5,091,501 discloses the conversion of certain cinnamic acid derivatives, under polyester-forming conditions and in the presence of suitable diol and acidic monomers, to form coumarin-containing polyesters. The diol and acidic monomers included 1,3-propanediol and terephthalic acid.
Krutak et al., in WO92/07913, describe polyester powders containing copolymerized therein at least 1% of a visible colorant. The colorant is introduced in solution in an organic solvent.
DiPietro in U.S. Pat. No. 6,103,006 discloses a fluorescent dye comprising: 3,4-benzoxanthrene dicarboxylic anhydride or the diacid (BXDA), a monomer having at least one carboxyl group, and a second monomer having at least one amine group or at least one alcohol group.
New and/or improved fluorescent polyesters are desirable. Fluorescent polyesters suitable for use in making fibers are also desirable. The present invention is directed to these and other important ends.